In U.S. Pat. No. 6,220,456 B1, Jensen et al. disclose a rack with two posts. A pair of rails are mounted on the posts respectively. Each of the rails includes two ribs, which jointly define a slot. Each slot has one end formed as a wide open end. A chassis has two lateral sides each mounted with a fixing member. The fixing members of the chassis can slide into the slots through the wide open ends respectively in order for the chassis to be supported.
As the foregoing arrangement may have insufficient load bearing capacity, the present invention was conceived as an improvement.